Astro Integration API

Astro Integrations add new functionality and behaviors for your project with only a few lines of code.

This reference page is for anyone writing their own integration. To learn how to use an integration in your project, check out our Using Integrations guide instead.

The official Astro integrations can act as reference for you as you go to build your own integrations.

• Renderers: lit, svelte, react, preact, vue, solid
• Libraries: tailwind, partytown
• Features: sitemap

interface AstroIntegration {
  name: string;
  hooks: {
    'astro:config:setup'?: (options: {
      config: AstroConfig;
      command: 'dev' | 'build';
      isRestart: boolean;
      updateConfig: (newConfig: Record<string, any>) => void;
      addRenderer: (renderer: AstroRenderer) => void;
      addWatchFile: (path: URL | string) => void;
      addClientDirective: (directive: ClientDirectiveConfig) => void;
      injectScript: (stage: InjectedScriptStage, content: string) => void;
      injectRoute: ({ pattern: string, entryPoint: string }) => void;
    }) => void;
    'astro:config:done'?: (options: { config: AstroConfig }) => void | Promise<void>;
    'astro:server:setup'?: (options: { server: vite.ViteDevServer }) => void | Promise<void>;
    'astro:server:start'?: (options: { address: AddressInfo }) => void | Promise<void>;
    'astro:server:done'?: () => void | Promise<void>;
    'astro:build:start'?: () => void | Promise<void>;
    'astro:build:setup'?: (options: {
      vite: ViteConfigWithSSR;
      pages: Map<string, PageBuildData>;
      target: 'client' | 'server';
    }) => void | Promise<void>;
    'astro:build:generated'?: (options: { dir: URL }) => void | Promise<void>;
    'astro:build:ssr'?: (options: { manifest: SerializedSSRManifest }) => void | Promise<void>;
    'astro:build:done'?: (options: { dir: URL; routes: RouteData[] }) => void | Promise<void>;
  };
}

Next hook: astro:config:done

When: On initialization, before either the Vite or Astro config have resolved.

Why: To extend the project config. This includes updating the Astro config, applying Vite plugins, adding component renderers, and injecting scripts onto the page.

'astro:config:setup'?: (options: {
  config: AstroConfig;
  command: 'dev' | 'build';
  isRestart: boolean;
  updateConfig: (newConfig: Record<string, any>) => void;
  addRenderer: (renderer: AstroRenderer) => void;
  addClientDirective: (directive: ClientDirectiveConfig) => void;
  addWatchFile: (path: URL | string) => void;
  injectScript: (stage: InjectedScriptStage, content: string) => void;
  injectRoute: ({ pattern: string, entryPoint: string }) => void;
}) => void;

Type: AstroConfig

A read-only copy of the user-supplied Astro config. This is resolved before any other integrations have run. If you need a copy of the config after all integrations have completed their config updates, see the astro:config:done hook.

Type: 'dev' / 'build'

• dev - Project is executed with astro dev or astro preview
• build - Project is executed with astro build

Type: boolean

false when the dev server starts, true when a reload is triggered. Useful to detect when this function is called more than once.

Type: (newConfig: Record<string, any>) => void;

A callback function to update the user-supplied Astro config. Any config you provide will be merged with the user config + other integration config updates, so you are free to omit keys!

For example, say you need to supply a Vite plugin to the user’s project:

import bananaCSS from '@vitejs/official-banana-css-plugin';

export default {
  name: 'banana-css-integration',
  hooks: {
    'astro:config:setup': ({ updateConfig }) => {
      updateConfig({
        vite: {
          plugins: [bananaCSS()],
        }
      })
    }
  }
}

Type: (renderer: AstroRenderer ) => void; Examples: lit, svelte, react, preact, vue, solid

A callback function to add a component framework renderer (i.e. React, Vue, Svelte, etc). You can browse the examples and type definition above for more advanced options, but here are the 2 main options to be aware of:

• clientEntrypoint - path to a file that executes on the client whenever your component is used. This is mainly for rendering or hydrating your component with JS.
• serverEntrypoint - path to a file that executes during server-side requests or static builds whenever your component is used. These should render components to static markup, with hooks for hydration where applicable. React’s renderToString callback is a classic example.

Type: URL | string

If your integration depends on some configuration file that Vite doesn’t watch and/or needs a full dev server restart to take effect, add it with addWatchFile. Whenever that file changes, the Astro dev server will be reloaded (you can check when a reload happens with isRestart).

Example usage:

// Must be an absolute path!
addWatchFile('/home/user/.../my-config.json');
addWatchFile(new URL('./tailwind.config.js', config.root));

Type: (directive: ClientDirectiveConfig ) => void;

Adds a custom client directive to be used in Astro files. As this is an experimental feature, you also need to enable the experimental.customClientDirectives configuration option to use this API.

Note that directive entrypoints are only bundled through esbuild and should be kept small so they don’t slow down component hydration.

Example usage:

// Create a `client:click` directive
addClientDirective({
  name: 'click',
  entrypoint: 'astro-click-directive/click.js' 
})

/**
 * Hydrate on first click on the window
 * @type {import('astro').ClientDirective}
 */
export default (load, opts, el) => {
  window.addEventListener('click', async () => {
    const hydrate = await load()
    await hydrate()
  }, { once: true })
}

You can also add types for the directives in your library’s type definition file:

declare module 'astro' {
  interface AstroClientDirectives {
    'client:click'?: boolean
  }
}

Type: ({ pattern: string, entryPoint: string }) => void;

A callback function to inject routes into an Astro project. Injected routes can be .astro pages or .js and .ts route handlers.

injectRoute takes an object with a pattern and an entryPoint.

• pattern - where the route should be output in the browser, for example /foo/bar. A pattern can use Astro’s filepath syntax for denoting dynamic routes, for example /foo/[bar] or /foo/[...bar]. Note that a file extension is not needed in the pattern.
• entryPoint - a bare module specifier pointing towards the .astro page or .js/.ts route handler that handles the route denoted in the pattern.

Example usage:

injectRoute({
  pattern: '/foo/[dynamic]',
  entryPoint: 'foo/dynamic-page.astro'
});

Type: (stage: InjectedScriptStage, content: string) => void;

A callback function to inject a string of JavaScript content onto every page.

The stage denotes how this script (the content) should be inserted. Some stages allow inserting scripts without modification, while others allow optimization during Vite’s bundling step:

• "head-inline": Injected into a script tag in the <head> of every page. Not optimized or resolved by Vite.

• "before-hydration": Imported client-side, before the hydration script runs. Optimized and resolved by Vite.

• "page": Similar to head-inline, except that the injected snippet is handled by Vite and bundled with any other <script> tags defined inside of Astro components on the page. The script will be loaded with a <script type="module"> in the final page output, optimized and resolved by Vite.

• "page-ssr": Imported as a separate module in the frontmatter of every Astro page component. Because this stage imports your script, the Astro global is not available and your script will only be run once when the import is first evaluated.

  The main use for the page-ssr stage is injecting a CSS import into every page to be optimized and resolved by Vite:

  injectScript('page-ssr', 'import "global-styles.css";');

  Copied!

Previous hook: astro:config:setup

Next hook: astro:server:setup when running in “dev” mode, or astro:build:start during production builds

When: After the Astro config has resolved and other integrations have run their astro:config:setup hooks.

Why: To retrieve the final config for use in other hooks.

'astro:config:done'?: (options: { config: AstroConfig }) => void | Promise<void>;

Type: AstroConfig

A read-only copy of the user-supplied Astro config. This is resolved after other integrations have run.

Previous hook: astro:config:done

Next hook: astro:server:start

When: Just after the Vite server is created in “dev” mode, but before the listen() event is fired. See Vite’s createServer API for more.

Why: To update Vite server options and middleware.

'astro:server:setup'?: (options: { server: vite.ViteDevServer }) => void | Promise<void>;

Type: ViteDevServer

A mutable instance of the Vite server used in “dev” mode. For instance, this is used by our Partytown integration to inject the Partytown server as middleware:

export default {
  name: 'partytown',
  hooks: {
    'astro:server:setup': ({ server }) => {
      server.middlewares.use(
        function middleware(req, res, next) {
          // handle requests
        }
      );
    }
  }
}

Previous hook: astro:server:setup

Next hook: astro:server:done

When: Just after the server’s listen() event has fired.

Why: To intercept network requests at the specified address. If you intend to use this address for middleware, consider using astro:server:setup instead.

'astro:server:start'?: (options: { address: AddressInfo }) => void | Promise<void>;

Type: AddressInfo

The address, family and port number supplied by the NodeJS Net module.

Previous hook: astro:server:start

When: Just after the dev server is closed.

Why: To run any cleanup events you may trigger during the astro:server:setup or astro:server:start hooks.

'astro:server:done'?: () => void | Promise<void>;

Previous hook: astro:config:done

Next hook: astro:build:setup

When: After the astro:config:done event, but before the production build begins.

Why: To set up any global objects or clients needed during a production build. This can also extend the build configuration options in the adapter API.

'astro:build:start'?: () => void | Promise<void>;

Previous hook: astro:build:start

Next hook: astro:build:ssr

When: After the astro:build:start hook, runs immediately before the build.

Why: At this point, the Vite config for the build has been completely constructed, this is your final chance to modify it. This can be useful for example to overwrite some defaults. If you’re not sure whether you should use this hook or astro:build:start, use astro:build:start instead.

'astro:build:setup'?: (options: {
  vite: ViteConfigWithSSR;
  pages: Map<string, PageBuildData>;
  target: 'client' | 'server';
}) => void | Promise<void>;

Previous hook: astro:build:setup

When: After a static production build has finished generating routes and assets.

Why: To access generated routes and assets before build artifacts are cleaned up. This is a very uncommon use case. We recommend using astro:build:done unless you really need to access the generated files before cleanup.

'astro:build:generated'?: (options: { dir: URL }) => void | Promise<void>;

Previous hook: astro:build:setup

When: After a production SSR build has completed.

Why: To get access to the SSR manifest, this is useful when creating custom SSR builds in plugins or integrations.

'astro:build:ssr'?: (options: { manifest: SerializedSSRManifest }) => void | Promise<void>;

Previous hook: astro:build:ssr

When: After a production build (SSG or SSR) has completed.

Why: To access generated routes and assets for extension (ex. copy content into the generated /assets directory). If you plan to transform generated assets, we recommend exploring the Vite Plugin API and configuring via astro:config:setup instead.

'astro:build:done'?: (options: { dir: URL; routes: RouteData[], pages: { pathname: string }[] }) => void | Promise<void>;

Type: URL

A URL path to the build output directory. Note that if you need a valid absolute path string, you should use Node’s built-in fileURLToPath utility.

import { writeFile } from 'node:fs/promises';
import { fileURLToPath } from 'node:url';

export default function myIntegration() {
  return {
    hooks: {
      'astro:build:done': async ({ dir }) => {
        const metadata = await getIntegrationMetadata();
        // Use fileURLToPath to get a valid, cross-platform absolute path string 
        const outFile = fileURLToPath(new URL('./my-integration.json', dir));
        await writeFile(outFile, JSON.stringify(metadata));
      }
    }
  }
}

Type: RouteData[]

A list of all generated routes alongside their associated metadata.

You can reference the full RouteData type below, but the most common properties are:

• component - the input file path relative to the project root
• pathname - the output file URL (undefined for routes using [dynamic] and [...spread] params)

interface RouteData {
  /** Whether a given route is an HTML page or non-HTML endpoint */
  type: 'page' | 'endpoint';
  /** Source component URL */
  component: string;
  /**
   * Output URL pathname where this route will be served
   * note: will be undefined for [dynamic] and [...spread] routes
   */
  pathname?: string;
  /** 
   * regex used for matching an input URL against a requested route
   * ex. "[fruit]/about.astro" will generate the pattern: /^\/([^/]+?)\/about\/?$/
   * where pattern.test("banana/about") is "true"
   */
  pattern: RegExp;
  /**
   * Dynamic and spread route params
   * ex. "/pages/[lang]/[..slug].astro" will output the params ['lang', '...slug']
   */
  params: string[];
  /**
   * Similar to the "params" field, but with more associated metadata
   * ex. "/pages/[lang]/index.astro" will output the segments
   * [[ { content: 'lang', dynamic: true, spread: false } ]]
   */
  segments: { content: string; dynamic: boolean; spread: boolean; }[][];
  /** 
   * Function to render component in-place from a set of input data.
   * This is typically for internal use, so call with caution!
   */
  generate: (data?: any) => string;
}

Type: { pathname: string }[]

A list of all generated pages. It is an object with one property.

• pathname - the finalized path of the page.

The astro add command allows users to easily add integrations and adapters to their project. If you want your integration to be installable with this tool, add astro-integration to the keywords field in your package.json:

{
  "name": "example",
  "keywords": ["astro-integration"],
}

Once you publish your integration to npm, running astro add example will install your package with any peer dependencies specified in your package.json. This will also apply your integration to the user’s astro.config like so:

import { defineConfig } from 'astro/config';
+ import example from 'example';

export default defineConfig({
+  integrations: [example()],
})

All integrations are run in the order that they are configured. For instance, for the array [react(), svelte()] in a user’s astro.config.*, react will run before svelte.

Your integration should ideally run in any order. If this isn’t possible, we recommend documenting that your integration needs to come first or last in your user’s integrations configuration array.

An integration can also be written as a collection of multiple, smaller integrations. We call these collections presets. Instead of creating a factory function that returns a single integration object, a preset returns an array of integration objects. This is useful for building complex features out of multiple integrations.

integrations: [
  // Example: where examplePreset() returns: [integrationOne, integrationTwo, ...etc]
  examplePreset()
]